Use of 4-chloro-3, 5-dinitrobenzotrifluoride (CNBF) Derivatization and Ultrahigh-performance Liquid Chromatography Tandem Mass Spectrometry for the Determination of 20 Free Amino Acids in Chinese Jujube Date

Ultrahigh-performance liquid chromatography tandem mass spectrometry with 4-chloro-3,5-dinitrobenzotrifluoride (CNBF) derivatization was developed for simultaneous determination of 20 free amino acids in Chinese jujube date. The MS/MS conditions, choice of mobile phase, the extraction process, and matrix effects were studied with a view to a method of optimization. The limits of detection for measurement of the amino acids ranged from 0.8 to 600.0 μg L^?1. The correlation coefficients (r²?≥?0.9947) indicated good correlation between the concentrations of amino acids and the peak areas for the CNBF-derivatives. Recoveries for samples spiked at 25.0, 50.0, and 100.0 mg kg^?1 ranged from 66.3 to 106.6 % (except tryptophan spiked at 25.0 and 50.0 mg kg^?1, which provided recoveries of 61.2 and 60.4 %, and tyrosine spiked at three different concentrations, which provided recoveries of 54.8–58.6 %), with relative standard deviation values of less than 9.1 %.     

Ionic Liquid-Based Dispersive Liquid–Liquid Microextraction Following High-Performance Liquid Chromatography for the Determination of Fungicides in Fruit Juices

This paper described an ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) combined with high-performance liquid chromatography (HPLC) method to determine fungicides in fruit juices. In this method, 1-hexyl-3-methyli-midazolium hexafluorophosphate (HMIMPF₆) was used as extraction solvent, which dispersed into the fruit juices under vigorously shaking with the vortex. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, vortex time, centrifugation time, sample pH, on the extraction efficiency were investigated. Under the optimum conditions, the linear correlation coefficients ranged from 0.9902 to 0.9979 for concentration levels of 0.02–2 mg l^?1, the extraction recoveries were ranged 66.2–92.9 % except pyrimethanil (39.5–44.6 %), The relative standard deviations (RSDs; n?=?6) ranged from 2.2 % to 11.6 %, and the limits of detection (LODs) for the fungicides were between 3.1 and 10.2 μg l^?1. Two real samples including apple and grape juices, spiked at two concentration levels were analyzed and yielded recoveries ranging from 71.3–93.1 % and 65.4–87.7 %, respectively.     

Analysis of Ascorbic Acid and Isoascorbic Acid in Orange and Guava Fruit Juices Distributed in Thailand by LC-IT-MS/MS

This work describes the determination of ascorbic acid (AA) and isoascorbic acid (IAA) in fruit juices by liquid chromatography coupled with ion trap tandem mass spectrometry (LC-IT-MS/MS), with a reversed phase column (C₁₈) and simple isocratic conditions of 0.1 % formic acid. The negative ion mode of electrospray ionization (ESI) and the MS/MS transition of m/z 175 were used for the quantitation of AA- and IAA-generated product ions with m/z 115. The method was validated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. Good linearity was achieved with 0.6 and 1.8 μg/mL for the LOD and LOQ, respectively. The intraday and intermediate precisions were approximately 4 and 7 %, respectively. Recovery percentages ranged from 88 to 108 %. All validation parameters were found to be within the acceptable range for both AA and IAA. Hence, the proposed method is suitable for simultaneously determining AA and IAA. Fourteen fruit juice samples were analyzed including fruit juices from supermarkets, local markets, and laboratory preparations. Ten fruit juice samples (100 %) from different brands in the supermarkets were investigated for AA and IAA content. AA could be detected in all the samples, ranging from 5.2?±?2 to 44.4?±?1.3 μg/mL, and the values of vitamin C in 4 guava samples were less than the values specified by the manufacturer. IAA was observed in 4 of 10 samples ranging from 3.4?±?0.9 to 78.3?±?3.9 μg/mL, and the highest value of IAA was approximately two fold higher than the highest value of AA. For freshly prepared fruit juices, AA was detected in both local market- and laboratory-prepared juices. The value ranged from 13.2?±?0.9 to 105.1?±?1.3 μg/mL. In addition, the AA stability after opening the package was evaluated. The results showed that after 4 days of storage in the refrigerator, approximately 30 and 15 % losses of AA were observed for the orange and guava juices, respectively. Fresh fruit juices were thus demonstrated to be good sources of AA, with the highest value observed for guava juice prepared in the laboratory.     

Sodium benzoate and potassium sorbate preservatives in food stuffs in Iran

A high-performance liquid chromatography method was applied for the determination of the levels of benzoate and sorbate in 400 food samples, including pickled cucumbers, canned tomato pastes, sour cherry jams, soft drinks, fruit juices and dairy products (UF-Feta cheeses, Lighvan cheeses, lactic cheeses, yogurts and doogh). The results showed that 270 (67.5%) of all samples contained benzoate ranging from 11.9 to 288.5 mg kg^?1 in lactic cheese and fruit juice, respectively. The levels of sorbate in 98 (24.5%) of the samples were 20.1 to 284.3 mg kg^?1 in doogh and fruit juice, respectively. Moreover, benzoate was detected in all dairy products ranging from 11.9 mg kg^?1 in lactic cheese to 91.2 mg kg^?1 in UF-Feta cheese. A low concentration of benzoate could originate naturally, due to specific biochemical mechanisms during cheese, yogurt and doogh maturation. In conclusion, a minimum level for benzoate in dairy products should be defined in the legislation.     

Determination of phthalate esters in non-alcoholic beverages by GC–MS and optimization of the extraction conditions

A quantificational method for 7 phthalate esters in non-alcoholic beverages was developed. Dimethyl phthalate, di-ethyl phthalate, di-propyl phthalate (DPP), di-butyl phthalate (DBP), benzyl butyl phthalate, di-(2-ethylhexyl) phthalate (DEHP), and di-octyl phthalate (DOP) were extracted from non-alcoholic beverages with the optimized solid-phase extraction method, and quantification was achieved by gas chromatography–mass spectrometry with isotope internal standard of d₄-di-(2-ethylhexyl) phthalate (DEHP-d₄). The inter-day method repeatability (RSD) was 8–13 %, whereas the intra-day method repeatability (RSD) was 9–15 %. The mean spiking recoveries were 84–105 %. A wide variety of phthalate concentrations was observed in 48 non-alcoholic beverages. DEHP was the most abundant phthalate compound followed by DBP, DPP, and DOP. DEHP was found in sport drinks (0.015–0.098 mg L^?1), tea (0.016–0.123 mg L^?1), coffee (0.028–0.159 mg L^?1), and fruit juices (0.022–0.126 mg L^?1).     

Vortex-Assisted Ionic Liquid Dispersive Liquid-Liquid Microextraction Coupled with High-Performance Liquid Chromatography for the Determination of Triazole Fungicides in Fruit Juices

A rapid, efficient, and environmentally friendly method using vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME) prior to high-performance liquid chromatography coupled with photodiode array detection (HPLC-PDA) has been developed for the determination of six triazole fungicides (triazolone, triadimenol, epoxiconazole, flusilazole, tebuconazole, and diniconazole) in various fruit juices. 1-Hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) and acetonitrile were used as extraction and dispersive solvents, respectively. A single factor experiment was selected to obtain the significant variables from the several related parameters that could affect the extraction efficiencies, such as the volume of IL and acetonitrile, extraction time, centrifugation time, and salt addition. Under the optimum conditions, an excellent linearity with correlation coefficients higher than 0.997 was obtained. Enrichment factors and average recoveries in three concentration levels ranged from 51 to 72, and 71.0 to 104.5 %, respectively, and the relative standard deviations (RSDs) from 1.4 to 11.8 %. The limits of detection (LODs) (S/N?=?3) for the six triazole fungicides were between 0.4 and 6.7 μg L^?1. The proposed method was successfully applied for the determination of trace amounts of triazole fungicides in various fruit juices including peach, apple, and orange juices.     

Comparison of fruit characteristics,oil properties and fatty acid composition of local Syrian Kaissy cv olive (<Emphasis Type="Italic">Olea europaea</Emphasis>)

Characterization of Syrian (Kaissy cultivar) olive fruits and evaluation of physic-chemical properties of oils were carried out during 3 years of production. The mean values of data for both measured and calculated variables of fruits were: grain length (21.89 mm), grain width (17.92 mm), length/width (1.22), weight of grain (3.79 g), weight of pulp (flesh) (3.19 g), weight of pit (0.60 g), pulp/pit ratio (5.35), crude oil (17.13%), water content (moisture) (51.34%). The 3 year average values of chemical properties of Syrian Kaissy cultivar olive oils (SKOO) including acid value, peroxide vale, Thiobarbituric acid value, iodine value(IV), saponification value, and phenolic content were 0.58%, 4.33 mEq O₂ kg^??1, 0.028 mg MDA kg^??1 oil, 90.77 g I₂, 100 g^??1, 194.91 mg KOH g^??1, and 218.08 g gallic acid kg^??1, respectively. Pefractive index (RI), and viscosity were 1.4666 nD at 25?°C and 139.56 mPa.s, respectively. However, the 2 years average values of Hunter’s color parameters of SKOO were; the lightness (L*= 66.91), redness (a* = 18.80), yellowness (b* = 29.08) and the color differences (?E?=?65.49). FA analysis of the SKOO used showed a high content of monounsaturated fatty acids (oleic acid 70.82% and palmitic acid 1.01%) and low polyunsaturated fatty acids (Linoleic acid 10.72% and Linolenic 0.82%) and saturated fatty acids (Palmitic 14.10% and stearic 2.57%). Results for 3 years production of Syrian Kaissy cultivar olive fruit and oil are discussed in detail.     

Simultaneous Determination of Squalene, α-Tocopherol and β-Carotene in Table Olives by Solid Phase Extraction and High-Performance Liquid Chromatography with Diode Array Detection

Olives, the fruit of the Olea europaea tree, are highly appreciated in olive oil and table olives (20 % of crops) not only for their flavor but also for their nutritional properties, especially for antioxidant compounds such as squalling (SQ), α-tocopherol (TH) and β-carotene (BC). This paper presents a new analytical method for simultaneously determining SQ, TH and BC in table olives by using solid phase extraction (SPE) and high performance-liquid chromatography with diode array detection (HPLC-DAD), avoiding the classic saponification process. The correlation coefficients of calibration curves of the analyzed compounds ranged from 0.998 to 0.999, and the recoveries were in the range of 89.4–99.6 %. The validated method was used to analyze 30 table olive samples from Italy for their content of SQ (537–1,583 mg kg^?1), TH (21–90 mg kg^?1) and BC (0.4–2.6 mg kg^?1). Finally, experiments with HPLC-MS were conducted to compare this novel method with the classic saponification procedure.     

Free Amino Acids and Other Nitrogenous Fractions in Wine Grapes

SUMMARY: The concentration of eight free amino acids, total nitrogen, amino-acid fraction nitrogen, and nonamino-acid-fraction nitrogen in the juices of 26 red- and 23 white-wine varieties of grapes was determined at early and late stages of fruit maturity. Proline was the most prominent amino acid in 31 of the varieties at early harvest and in 45 of the varieties at late harvest while arginine was the main amino acid in 16 and 3 varieties at early and late harvest, respectively. "Salvador" and "Scarlet" were the only varieties in which α-alanine was the predominant amino acid. The concentration of total nitrogen in the juices of the various varieties ranged from 44 to 256 mg/100 ml and the amino-acid fraction nitrogen ranged from 26 to 171 mg/100 ml juice. The amino acid fraction and nonamino acid fraction nitrogen in the juices ranged from 53 to 76% and 23 to 56% of total Kjeldahl nitrogen respectively. Alanine, γ-aminobutyric acid, arginine, aspartic acid, glutamic acid, proline, serine and theronine accounted for 29 to 72% of the total nitrogen and 47 to 96% of the amino acid fraction nitrogen. Arginine contributed the most nitrogen of the amino acids, accounting for 6 to 44% of the total nitrogen in the juices of the various fruits.     

Determination of Free Amino Acids in Coated Foods by GC–MS: Optimization of the Extraction Procedure by Using Statistical Design

The development and validation of an extraction procedure for quantification of free amino acids in coated products by MTBSTFA derivatization and GC–MS detection is described. The extraction method entailed the sample homogenization with hydrochloric acid (HCl) by stirring at 40 °C followed by two centrifugation steps. The optimum combination of the extraction variables was achieved by response surface methodology. HCl concentration and volume and stirring time influenced free amino acid extraction yield. The selected optimal extraction conditions were 5 g of sample mixed to 7.5 ml of 0.1 N HCl and stirred during 90 min. Consistency between predicted and experimental values as well as in the quality parameters was observed. The calibration curves were linear within the range 5–100 μg ml^?1 with correlation coefficient values (R ² ) higher than 0.99. Detection and quantification limits of the analytical procedure ranged from 2.10^?5 to 18.10^?2 μg μl^?1 and from 8.10^?5 to 60.10^?2 μg μl^?1, respectively. Precision was 0.20–12.59 % for run-to-run and 3.38–17.60 % for day-to-day. The accuracy is between 82.99 and 115.77 %. Nineteen amino acids were analyzed in frozen-thawed and deep-fried coated products from different origin, with cysteine being the most relevant.     

Rapid Residue Determination of Cyenopyrafen in Citrus Peel,Pulp, and Whole Fruit Using Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry

A sample pretreatment method was established to analyze the residues of cyenopyrafen in citrus peel, pulp, and whole fruit using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The target compound was extracted from all matrices with acetonitrile and then cleaned by dispersive solid phase extraction using 10 mg GCB?+?150 mg MgSO₄ for citrus peel; 50 mg PSA?+?150 mg MgSO₄ for citrus pulp, and 50 mg C18?+?50 mg PSA?+?150 mg MgSO₄ for whole fruits. Determination of the target compound was achieved in less than 5.0 min using an electrospray ionization source in positive mode. Average recoveries in citrus peel, pulp, and whole fruit spiked at 0.01, 0.2, and 2 mg kg^?1 ranged from 84.9 to 105.1%, with relative standard deviations (RSD_r) of 0.7–7.9%. The reproducibility (RSD_R) ranged from 2.6 to 6.8%. The limits of detection and quantification ranged from 0.00032 to 0.0012 mg kg^?1 and from 0.0009 to 0.0036 mg kg^?1, respectively. This method was used to determine cyenopyrafen residues in citrus fruits to study its dissipation under field conditions. The trial results showed that the half-lives of cyenopyrafen in whole fruits were 10.2 and 6.2 days in Hunan and Guangxi provinces, respectively. The developed analytical method provides a basis to establish maximum residue limits and monitor cyenopyrafen residue in citrus.     

Detection of 5-hydroxymethyl-2-furfural Levels in Selected Chinese Foods by Ultra-High-Performance Liquid Chromatograph Analytical Method

In this study, an ultra-high-performance liquid chromatography method was developed to detection the levels of 5-hydroxymethyl-2-furfural (HMF) in 227 selected food products obtained from the Chinese markets. The performance of the analysis method was evaluated by some quality parameters such as limit of detection (LOD), limit of quantification (LOQ), linearity, recovery, and run-to-run (n?=?6) and day-to-day (n?=?18) precisions. The LOD and the LOQ of the method in different food matrices ranged from 0.15 to 0.50 and from 0.35 to 1.20 mg kg^?1, respectively. The results from this study showed that HMF was mostly detected in all samples selected. HMF contents in different samples varied greatly according to the raw materials and processing conditions. The highest level of HMF was found in preserved fruits and ground coffee, with average levels of 409.6 and 409.9 mg kg^?1, respectively. Preliminary estimates of HMF exposure from foods in the Chinese population was estimated to be 0.12 mg kg^?1 body weight day^?1, which is relatively low compared with the result reported by JECFA and European Food Safety Authority.     

Determination of Pesticides Residues in Brazilian Grape Juices Using GC-MS-SIM

The production of grape juice in Brazil is growing at a 30 % rate a year. To increase exports, a full complainment to food safety protocols, as those in the Codex Alimentarius, is mandatory. Simple and fast analytical methods are needed for quality assurance. The objective of this work was to develop and validate an analytical method for detection of pesticides residues (organochlorides, organophosphorides, and fungicides) in Brazilian whole grape juices. The analyses were performed by gas chromatography coupled to mass spectrometry, operating in selective ion monitoring. After liquid–liquid extraction, samples were preconcentrate using solid-phase extraction in Florisil. The limit of quantification ranged from 3.75 to 9.47 mg l^-1, and recovery varied from 84.0 % to 99.7 %, with RSD lower than 4.9 %. From a total of 99 Brazilian grape juices analyzed, pesticide residues were found in 32.     

Effect of Amino Acids on Microwave Dielectric Properties of Minced Antarctic Krill (<Emphasis Type="Italic">Euphausia superba</Emphasis>)

The dielectric properties of ten solid amino acids, namely, glycine, proline, cysteine, glutamine, lysine, methionine, histidine, arginine, tyrosine, and tryptophan, and the effects of amino acid concentrations (0, 1, 3, and 5%) on the dielectric properties of minced Antarctic krill (Euphausia superba) were studied within a frequency range of 300–3000 MHz at 20.0 ± 0.5 °C. The dielectric constants and dielectric loss factor of amino acids were 2.0 ± 0.4 and 0.2 ± 0.3, respectively (moisture contents, 0.05–0.33%), except those of lysine (5.5 ± 0.5 and 1.5 ± 1.0, respectively) (moisture content, 4.5%). The dielectric properties of non-polar, neutral-polar, alkaline amino acids added to Antarctic krill were affected by the frequency and moisture contents, molecular weight, and isoelectric points (pI) of amino acids. As the molecular weight and pI values increased, the critical frequencies of aliphatic amino acid added to minced Antarctic krill decreased, whereas heterocyclic amino acid added to minced Antarctic krill increased. Quantitative relationships between parameters that define both the real and the imaginary parts of the Debye relations and the weight fraction of amino acid contents in Antarctic krill were determined. Moreover, glycine (at 5%) or lysine (at 5%) significantly influenced the dielectric constants and dielectric loss factor of minced Antarctic krill (p < 0.05) but did not have significant effects on temperature history and distribution (p < 0.05) during microwave heating at 2450 MHz.     

Using capillary isotachophoresis for the determination of biogenic amines and D‐isocitric acid in food products

This paper presents results achieved in the determination of biogenic amines in various food products and quality evaluation of some commercial orange juices by capillary isotachophoresis. The highest amount of histamine was determined in frankfurters (146.75 mg·kg^–1); the content of tyramine was either under detection limit of method or it was present in very low concentrations. The highest amount of cadaverine was determined in Kari?ka cheese (666.36 mg·kg^–1). The limit of determination was 1.59 mg·kg^–1 for histamine and 1.25 mg·kg^–1 for tyramine. The recovery of method ranged from 95.4 to 104.9%. Surprisingly it was found that many organge juice samples did not reach required values according to the Code of Practice. The lowest ratio of citric to D ‐isocitric acids was found in Happy day juice (44.1). Limit of determination was 1.62 mg·dm^–3 for citric acid and 2.00 mg·dm^–3 for D ‐isocitric acid. The recovery of the method ranged from 89 to 96.5%.     

Main Organic Acids in Rice Wine and Beer Determined by Capillary Electrophoresis with Indirect UV Detection Using 2, 4-Dihydroxybenzoic Acid as Chromophore

A rapid and sensitive analytical method for the determination of main organic acids in wines was developed by capillary electrophoresis (CE) with indirect UV detection. Separation parameters including the pH of electrolyte, chromophore, and its concentration were optimized. The results showed that the optimal electrolyte for the separation of organic acids consisted of 10 mmol L^?1 2, 4-dihydroxybenzoic acid (DHBA) at pH 3.6 containing 0.4 mmol L^?1 cetyltrimethlammonium bromide (CTAB). DHBA as chromphore was selected based on the close mobility to the analyte and relatively large molar extinction coefficient. The method showed good linearity with limits of detection (LOD), ranging from 0.5 to 7.5 mg L^?1. The relative standard deviation (RSD) of interday precisions for the peak area and the migration time were less than 7.2 and 0.8 %, respectively. The recoveries of the analyte in Chinese rice wine sample were between 90.3 and 106.9 % with RSD ranging from 1.4 to 8.9 %. The method was successfully applied to the commercial rice wine and beer samples with dilution and filtration.     

Monitoring of 29 weight loss compounds in foods and dietary supplements by LC-MS/MS

Because of the rapid growth in dietary supplement availability and public concern for weight control, the investigation of foods and various dietary supplements illegally adulterated with weight loss compounds has become increasingly important. A total of 29 weight loss compounds, including sennoside, sibutramine, ephedrine and their analogues, found to be adulterated in foods and dietary supplements were simultaneously examined by LC-MS/MS. The 188 samples were collected between 2009 and 2012 in South Korea, and method validation was performed to determine the adulterants to the weight loss compounds. LODs, LOQs and linearity ranged from 0.03 to 7.5 ng ml^?1, from 0.08 to 30.00 ng ml^?1, and from 0.990 to 0.999, respectively. The results showed that nine weight loss compounds, namely bisacodyl, desmethylsibutramine, didesmethylsibutramine, ephedrine, fluoxetine, pseudoephedrine, sennoside A, sennoside B and sibutramine, were detected in 62 of all collected samples and were found in order of frequency as follows: sibutramine, 25.7%; sennoside A, 22.9%; sennoside B, 20.0%; fluoxetine, 8.6%; desmethylsibutramine, 7.1%; bisacodyl, ephedrine, and pseudoephedrine, 4.3%; and didesmethylsibutramine, 2.9%. Sibutramine, which was the most frequently found adulterant, ranged in levels from 0.03 to 132.40 mg g^?1 (2010), from 0.88 to 76.2 mg g^?1 (2011), and from 0.07 to 0.24 mg g^?1 (2012). Although the concentrations of most compounds ranged widely, some compounds such as bisacodyl and fluoxetine were found at high concentrations in several samples.     

A comparative study for determination of biogenic amines in meat samples by capillary isotachophoresis with two electrolyte systems

The selected biogenic amines, BAs (putrescine, cadaverine, histamine, tyramine, spermidine and spermine), in pork, beef, and poultry meat samples were determined by two simple procedures without derivatization using isotachophoretic technique. Two electrolyte systems were proposed for their separation and determination with satisfactory separation parameters. The linearity of the proposed procedures was between 2–10 mg L^?1 and 5–50 or 10–60 mg L^?1, whereas average recoveries for the standard solutions of amines and their mixture varied between 99–100 % and 95–105 %, respectively. Average recoveries for standard addition method (96–99 %) indicated satisfactory accuracy of proposed electrolyte systems. The obtained coefficient of variation values for standard solutions and meat samples ranged from 0.62 to 4.54 % and from 0.56 to 6.03 %, respectively, which confirmed good repeatability. Except for spermidine and spermine, BAs levels in fresh meat samples were generally low. The effect of storage time on the content of biogenic amines in meat was also studied indicating the increase of BAs levels (excluding Spermine and Spermidine).